Air conditioning process and apparatus



Sept. 14, 1937. J. N. HADJISKY AIR CONDITIONING PROCESS AND APPARATUS Filed June 5, 1933 F/GZ F/G. J

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gusty/z 92; Wad Yak] BY w4,%;7 e H/s ATTO EYS Patented Sept. 14, 1937 PATENT OFFICE .Am. CONDITIONING rnoonss AND APPARATUS Joseph N. Hadjisky, Birmingham, Mich.

Application June 5, 1933, Serial No. 674,297

18 Claims.

This invention relates to air conditioning processes and apparatus, and more particularly to an improved air conditioning system whereby in a novel and simple manner the humidity and temperature of the air in a served zone may be modified and held at desired levels.

An important object of the invention is the provision of an improved air conditioning system utilizing but a single corrective agency for controlling both temperature and humidity.

Another important object is the provision, in an air conditioning system utilizing but a single corrective agency, of means for regulating the functioning of such agency in response to both humidity and temperature conditions in the served zone.

A further object is the provision of such a conditioning system utilizing a circulating fluid for varying the temperature and humidity, and

means for regulating the flow of the circulating fluid by separate controlling means operating in parallel, and in turn for operating one of such controlling means in response to humidity and the other in response to temperature conditions in the served zone.

suitable apparatus for accomplishing the aforementioned objectives in a novel structural arrangement which is not only simple, cbmpact and economical, but eliminates all necessity for utilizing special insulation to prevent undesired heat leakage and sweating or accumulation of condensate upon the apparatus or housing, and converts some of the-latent heat removed by condensation into sensible heat eifect.

Other objects and advantages will be apparent from the following description, wherein reference is made to the accompanying drawing illustrating a preferred embodiment of my invention and wherein similar reference numerals designate siinilar parts throughout the several views.

In the drawing:

Figure 1 is a schematic diagram of a suitable arrangement of apparatus operable in accordance with my invention, showing the corrective agency and controlling means, and the method of connecting the same;

Figure 2 is a sectional view taken longitudinally through the housing of an air conditioning unit Means for circulating the air over the coils is also A still further object is the incorporation of ing and dehumidifying air, any suitable refrigerating agency may be used, and as will subsequently be explained, this single agency is used to effect both cooling and dehumidiflcationdespite which double use, however, the amounts of 5 cooling and of dehumidification effected are accurately and individually controllable. Reference to schematic Figure l of the drawing will assist in understanding the various steps of and functions involved in the process. A single re- 10 frigerating agency is provided for performing both latent and'sensible heat removal, and is represented by cooling coils l1. These are shown connected to a suitable source of cold water, al-

though the nature of the cooling medium is un- 15 provided, represented by the fan", the air movement being indicated by arrows l6. The cold water inlet designated "a is controlled by separate valves, designated 40, II, the first connected to and opened by a thermostat and the latter similarly connected to a hygrostat, which instruments may be located in the served zone. Preferably the humidity-responsive valve 4| controls a much greater proportion of the flow than the temperature-responsive valve 40, when both are 5 open; valve 40 permitting only a restricted flow even when fully open, the purpose of which restriction will presently appear. If cold water is used, a cooling coil temperature of about 39 is very satisfactory, and water, as is well known, is 40 easily and economically coolable to this temperature. The process may be additionally controllable by a damper as connected to and operable by the .thermostat T, or an independent thermostat if desired, (not shown) in such man- 45 ner that the air flow across the cooling coils may be reduced thereby in event the temperature of the conditioned zone falls too low.

Before discussing the operation of either the process in general or the illustrative arrangement of apparatus in particular, it should be pointed out that their successful operation, which makes possible substantially independent control of the temperature and humidity values of the air in a conditioned zone bymeans of a single marized as the much greater afilnity of an object,

whose temperature is below the dew point of the air, for latent heat than for sensible heat. That is to say, when humid air, the heat load of which is represented partly by latent heat carried by its water vapor, andpartly by sensible heat, comes in contact with an object whose temperature is below its dew point, a much greater proportion of the heat transfer which takes place will be of latent heat of vaporization, the surrender of which causes condensation of water vapor, than will be represented by the surrender of sensible heat, and this condition continues so long as the dew point of the air remains above the temperature of the cooling agency, whereas if the cooli agency be above the dew point of the air, but cooler than the air, the entire portion of the heat transfer will be of sensible heat, as a result of which latter transfer the temperature'of the air may be reduced without materially reducing its moisture load. It should further be noted that summer air of the sort which needs conditioning to render persons comfortable who must live in it, is ordinarily both warm and humid, so that when fresh air is supplied to an enclosure it brings both latent and sensible heat, in relative quantities not varying materially from equal proportions. The presence of people in the room or other area being conditioned, for-example, causes the constant addition to the air not only of sensible heat, but of water vapor in considerable quantities, although if no persons are present and only leakage of heat occurs, the heatthereby added may be almost entirely sensible. The proportion of latent to sensible heat being added to the air therefore ordinarily is continuously variable.

It is the tendency of a cold object tofirst and preferably expend its heat absorbing power principally in the removal of latent heat, by condensation of water vapor, "while only in a' secondary way is its energy available for the removal Y of sensible heat,-which forms one ofthe important bases of operation of my preferred process.

In order that the flow of the cooling medium may ordinarily desirable that the removal of sensible be properly responsive to both temperatureand humidity conditions in the served zone, two valves, as Ill-4|, are arranged in parallel relation in the inlet line i M, as best shown in Figure 1, each adapted to control the flow of the refrigerating medium. Valve 4|! is responsive to the control of a thermostat T, while valve 4| is subject to the control of a hygrostat H, the: hygrostat and thermostat being of course located in the conditioned zone, or in contact with air from the conditioned zone. The controlling instruments are so adjusted that upon a rise of temperature beyond a predetermined point the thermostat T opens the valve 40 and maintains it open until the temperature has fallen to a desired level, while the hygrostat H performs the same service in operating the valve 4| toward open and closed positions respectively as the humidity in the conditioned zone tends to rise and fall.

Bearing these facts in mind, it will be seen that while valve ll is held open, by reason of excessive humidity in the conditioned zone, the coils I! will be maintained at a reduced temperature which is closer to the temperature of the cooling water or other refrigerating agency than when only the temperature controlled valve 40 is open. The temperature of the cooling agency and rates of flow thereof are such, moreover, that when the valve ll is open the coils are held at a tempera-v ture well below the dew point of all air ordinarily encountered in summer and needing dehumidification. When the valve ll is closed and only valve 40 is open, the amount of cooling medium is so reduced that the coils are soon warmed by the air flowing over them to a point above the dew point temperature of the air, altho they remain sumciently cooler than the air to continue to remove sensible heat. During the period before the coils warm up, a small amount of condensation continues to take place. This can beadjusted to any desired amount and usually amounts to about 10 per cent or 20 per cent of the total moisture needed to be removed. During the next stage of cooling, when the cooling medium is warmed up and the cooling is carried on at a temperature above the dew point of the air, no more latent heat is removed. During this period, when the valve II is closed and only valve 40 is open, the air leaving the coils I! is always at lower relative humidity than when both valves 40 and ll are open, and at such time the warm air passdividing partition 26, and causes some of the condensation on the bottom to re-evaporate. Thus while some moisture is condensed by coil II when only valve 40 is open during the period before the coil warms up, it is re-vaporized as soon as it falls on the sheet 26, so that the net result of the process is removal of sensible heat only.

When both valves 40 and 4| are open, or when only valve 4| is open, due to the larger amount of cooling done, the relative humidity of the air leaving the coil i1 is much higher and its ability to pick up moisture is very much reduced so that the warming up action of the relatively warm air in the bleeder passage is unable to cause the same degree of re-evaporation as in the preceding case.

When the valve 4| has closed by reason of reduction of the humidity in the conditioned zone to a desired value, ordinarily well below the maximum comfortable level, more sensible heat may remain to be removed in order to properly reduce the temperature, although whether this is so or not, the continuing addition of heat makes it heat should continue.

In this process, it is not intended to regulate the temperature of the cooling mediumvery closely, so long as it remains a few degrees below the dew point of the air of the conditioned space.

If, however, the cooling medium should be supplied at a very low temperature, say 32 F., or less, and the maximum flow not properly adjusted, the air might be cooled more than necessary while valve 4| remained open. To avoid this the room thermostat may be connected to act upon the damper 28 in addition to the valve 40, and by opening the damper by-pass air directly to the discharge duct. This is not expected to be necessary if the humidity control instrument is sensitive and does not fall out of calibration. For that reason the damper operation can be connected to a second room thermostat set to operate at a temperature one or two degrees lower than the thermostat operating the valve 40.

The suggested use of cold water will be seen to be merely a practical consideration in the interests of economy. For the same considerations the valves 40- may be so constructed that they are never fully closed, and a small reduction of cooling-and dehumidifying effect may be obtained as long as the fan is running. Such combination will be dictated by such considerations and the space to be conditioned. I

In the structural embodiment shown in Figures 2 and 3, reference character I designates a suitable metal housing partly divided horizontally by a partition I 2 which serves as a support for blower fans I, and theirdriving motor l5. Within the cabinet III, which may be of sheet metal, is arranged the sinuous finned cooling coil II, shown suspended in spaced relation to the side walls of the cabinet and bounded upon one side by a partition l5 which dividesthe lower section of the cabinet into two vertical passageways, a downflow passage 30, and an upflow passage 3|. The bottom wall of the cabinet may be formed of sheet metal, and is preferably cylindrically curved as shown, and provided at a low point with a drain, as 22, for conducting away condensate.

Upon its side nearest the side wall of the cabinet the coil is bounded by a vertical partition 24 which forms a continuation of a spaced inner bottom wall orpartition 26, thetwo together defining a bleeder passage 32. The inner wall 26 may extend in spaced relation but parallel to the outer bottom wall 20, and preferably also extends up within the upfiow or outlet passage, where it ends and the bleeder passage discharges.

A damper 28 forms an upper continuation of the central partition I! and is soarranged that when closed (in which position it is shown in full lines in Figure 3) it directs the output of the fans l4 into the downfiow passage 30 and bleeder passage 33, the majority thereof of course passing over the coils ll, while a smaller quantity is delivered to the bleeder passage. It will be seen that the downward flow is reversed by the curved bottom walls 20-26, the air being turned and de livered in an upward direction through the right hand upflow section 3|. Connected to the passage 3i and forming an upward continuation by suitable air filters, as 35, the details of construction'of which, forming no part of this invention, need not here be considered.

1 The damper 26 may be provided with suitable operating mechanism such as the thermostatically controlled fluid motor 31, adapted to'swing it from the aforementioned position in which it is shown in full lines to the position in which it is shown in dotted lines in Figure 3, in which it greatly restricts air flow over the conditioning coils l1 and permits most of the air delivered by the fans to be by-passed directly to the outlet 32 through the damper opening. s

As pointed out in the more general description of the process, separate temperature and humidity-controlled valves 40- for throttling the flow of refrigerant may be provided.

The fiow of cooling fluid admitted by valve 40 is so proportioned to the cooling surface of the coil that it can take care of the purely sensitive heat load". This load is defined as that portion of heat infiltration to the conditioned space which is not accompanied by latent heat or moisture infiltration. It is also so proportioned that the temperature of the cooling medium is raised to a higher degree than the dew point'of the air when only this valve is open. The proportioning is also based on the capacity ofthe bleeding air to revaporlze a good portion of the condensate dripping upon sheet 26, as explained above.

The fiow of cooling medium passing thru the valve 4| is determined from the total dehumidification load which is defined as the latent heat load which is also accompanied by sensible heat; The amount of cooling medium admitted by this valve is set so that when'the maximum total dehumidification heat load is absorbed, the temperature of the cooling medium will still remain a few degrees below the dew point of the air to be conditioned.- Both the thermostat and hygrostat may be located in theinlet chamber l3 rather than in the open space of the conditioned zone itself. I

An outer hood or cover, as 36, provided with suitable inlets as 39 appurtenant the air filters ,35 may be provided, adapted to cover the entire same refrigerating agency is important, but that the structural features and. arrangement of the shown embodiment might be varied as desired to suit particular conditions.

It should also be noted, however, that the interposition of the bleeder or by-pass passage 33 between refrigerating coils and the outer cabinet walls prevents condensation upon the outer walls and eliminates the necessity of using insulation at this point. air serves to effectively insulate the outer wall from the innercompartment, and so prevent the temperature of the outer wall from falling to a point which would cause condensation on its surface. Condensation which occurs .on the inner wall is collected and conducted away from the unit through the suitably positioned drain 22, whlch may be connected to a seweror the like (not shown) while the inner curved bleeder partition 26 is also apertured at its bottom, as at 23,

so that condensate. may flow to the drain.

It should also be noted that in the structural embodiment shown and described, the airflow is in the same direction as the path taken by condensate. The flowing air therefore tends to sweep condensate on the coils and toward the receptacle at the. bottom of the'housing. This helps greatly in keeping the resistance of the cooling coils at a minimum, and avoids the undesirable effect of increased air resistance present in most constructions wherein the con-. -densate must fall off the coils in a different direction from that in which the air is proceeding, and in which as a result, the water which gathers on the coils in considerable quantities increases their air resistance materially.

While it will be apparent that the illustrated embodiment of my invention disclosed herein is well calculated to adequately fulfill the objects and advantages primarily stated, it is to be understood that the invention is-susceptible to variation, modification and change within the spirit and scope-of the subjoined claims.

What I claim is:

l. A process of cooling and dehumidifying air The relatively warm untreated which includes circulating a refrigerant whose temperature when supplied is held below the dew point temperature of the conditioned air but conditioned, means independently responsive to humidity and temperature conditions in a served zone for regulating the effective heat absorbing capacity of said cooling element, means for circulating air over such element, means including a damper movable to a positionjn which it restricts but does not completely prevent airflow over said element, and means responsive to a predetermined temperature drop in the served zone for moving said damper to such position while. the cooling element remains at such reduced temperature.

3. In an air conditioning device having an air inlet and an outlet, a single refrigerating system for cooling and dehumidification incorporating a circulatory refrigerant and with which air flowing from the inlet to the outlet may be passed in heat exchange relation, means responsive to the humidity conditions in a served zone for regulating refrigerant flow through said system and which when set for maximum flow enables maintenance of said system below the dew point of air to be treated, and additional means responsive to temperature conditions in the served zone for regulating a smaller proportion of refrigerant flow through said same system, and which when set for maximum flow is insufficient to maintain .the system below the dew 'point of air to be treated.

4. In an air conditioning device having an air inlet and an outlet, a single refrigerating system for cooling and dehumidiflcation incorporating a circulatory refrigerant and with which air flowing from the inlet to the outlet may be passed in heat exchange relation, means responsive to humidity conditions in 9. served zone for regulating refrigerant flow through said system and which when set for maximum flow enables maintenance of said system below the dew point of air to be treated,- additional means responsive to temperature conditions in the served zone for regulating a smaller proportion of refrigerant flow through said same system, and which when set for maximum flow is insufiicient to maintain the system below the dew point of air to be treated, and damper means also responsive to temperature conditions in the served zone for regulating the air flow.

5. In an air conditioning device' having an air inlet and an outlet, asingle refrigerating system I for cooling and dehumidiflcation incorporating a circulatory refrigerant and with which air flowing from the inlet to the outlet maybe passed in heat exchange relation, means responsive to humidity conditions in a served zone for regulating refrigerant flow through said system and which when set for maximum flow enables maintenance of said system below the dew point of air to be treated. additional means responsive to temperature conditions in the served zone for regulating a smaller proportion of refrigerant flow through said same system, and which when set for its maximum flow is insuflicient to maintain the system below the dew point of air to be treated,

' means so arranged that air must pass thereover after leaving the refrigerating system to reach the outlet for catching condensate, whereby condensate maybe absorbed by air above the dew point when only the temperature-responsive means is active.

6. The process of conditioning air which includes circulating a cooling agency whose temperature is held below the dew point temperature of the conditioned air but not otherwise closely regulated, passing air to be conditioned in heat conductive relation with said agency, controlling a major portion of the flow of such cooling agency in response to humidity conditions in the served zone, and controlling a smaller proportion of the total possible flow of the same agency in response to temperature conditions in the servedzone.

' '7. The method of treating air to be conditioned which includes circulating a refrigerant at a temperature below the dew point of the treated air, controlling the flow of a part of said refrigerant in response to humidity conditions in the served zone, regulating the flow of a smaller proportion 'of such flow in response to temperature conditions in the served zone, passing the entire regulated flow in heat exchange relation with the flow of air to be conditioned, and limiting the maximum flow of the smaller temperature regulated proportion to such extent that it is insuflicient to maintain the effective temperature of the refrigerant below the dew point.

8. The method of treating air to be conditioned which includes circulating a refrigerant at a temperature below the dew point of the treated air, passing refrigerant through a cooling element of fixed efiective surface area located in the path of air to be treated, regulating the flow of refrigerant through such element in response to elevation of humidity in the served zone above a desired level to allow sufficient flow through the cooling element to maintain said element below the dewpoint of the air, and in response to a rise of temperature only above a desired level, so

restricting the rate of flow through the cooling element that it is insuflicient to maintain the surface of said element below the dew point.

9. In an air conditioning device, a container having an inlet and an outlet, a cooling element therein, means for passing air to be conditioned through the container and over the cooling element, a condensate receiving portion within said.

container and nearer the outlet than the cooling element, measured along the path of air travel, and separate duct means for conducting relatively warm air through the container and in contact with a different part of said receiving portion independent of that contacted by condensate and by the air to be conditioned, whereby to warm said receiving portion by conduction and so promote revaporization of condensate therefrom.

10. A process of conditioning air which includes circulating a single refrigerant, passing air to be treated in heat exchange relation therewith, controlling a proportion of the total flow of refrigerant circulating in said system in response to variations of the purely sensible heat load of the air to be treated, and independently controlling'another portion of the total refrigerant flow through said same system reponsively to the relative humidity load of the air to be treated.

11. In an air conditioning device provided with means forming an inlet and outlet, a cooling element adapted to effect dehumidification by condensation of water vapor from the air being conditioned, condensate catch means nearer the outlet than said cooling element, means for circulating air from the inlet over said cooling element in the same general direction as the condensate must travel to reach the catch means, thence over the catch means and then to the outlet, and

means for passing untreated air in heat exchangerelation with said catch means.

12. In an air conditioning system a circulatory refrigerating system including a heat exchanger having a substantially fixed effective surface area, means for supplying refrigerant to said heat exchanger, regulating means for varying the rate of flow of refrigerant through said heat exchanger, temperature-responsive controlling means for said regulating means for varying such flow up to a maximum insufiicient to run the temperature of the surface of the heat exchanger down to the dew point of the air to be conditioned, humidityresponsive controlling means for said regulating means for varying such flow up to a maximum sufficient to run the temperature of the surface of thelheat exchanger below the dew point of the air to be conditioned, whereby the operation of the refrigerating means is independently controllable by either or both humidity and temperature, but the same heat exchanger may be held at a lower temperature by the humidity-responsive controlling means alone than by the temperatureresponsive controlling means alone.

13. Air conditioning apparatus including refrigerating means having a fixed effective surface area and through which a refrigerant may be circulated, means for inducing a flow of air thereover, and separate humidity and temperatureresponsive controlling means for regulating the rate of refrigerant circulation in said same refrigerating means.

14. Air conditioning apparatus including a refrigerating system including a heat exchanger having a fixed effective surface area and through which refrigerant may be circulated, means for inducing a fiow of air over said heat exchanger, and separate humidity and temperature-responsive controlling means operating in parallel upon and for regulating the rate of refrigerant flow in said heat exchanger.-

15. In air conditioning apparatus, a combined temperature andhumidity conditioning element comprising a single heat exchanger for circulatory refrigerant and having a fixed effective surface area, means for circulating refrigerant therethrough, means for inducing a fio-w of air to be conditioned over said exchanger, valving means for varying the flow of refrigerant through said exchanger, and controlling means independently responsive to humidity and temperature conditions in the served zone.for operating said valving means to control the flow of said heat regulating fiuid through said same exchanger in response to changes of temperature and humidity.

16. In an air conditioning device, a cabinet having air inlet and outlet portions, cooling and dehumidifying means comprising a heat exchanger within the cabinet over which air ispassed, said cabinet having spaced inner and outer wall portions, a by-pass conduit for air being cooled, formed at least partly by said spaced Wall portions and arranged to conduit air untreated directly from the inlet portion to the outlet portion, and the air passed thereover being guided during at least a portion of its travel by and in contact with the inner wall.

1'7. Air conditioning means comprising a single circulatory refrigerating system including a heat exchanger having a fixed effective surface area and operating by temperature differential for both humidity and temperature correction, means for circulating air to be conditioned over said heat exchanger, means for circulating refrigerant through said heat exchanger, valvular controlling means for said circulating means, and automatic regulating means for said valvular means responsive to both humidity and temperature conditions in the served zone for changing the rate of flow of refrigerant through said heat exchanger in response to both temperature and humidity conditions, to thereby control the operation of said single heat exchanger.

18. The process ofconditioning air which comprises circulating a heat-absorbing fluid through a single circulatory refrigerating system including a heat exchanger having a fixed effective surface area for absorbing heat from the air, and controlling the rate of flow of said fluid through said heat exchanger in response to both temperature and humidity conditions in the conditioned zone.

JOSEPH N. HADJISKY. 

